English Speech

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Today I want to talk to you about what happens in your brain when you have a mental illness and what can cause this. I will be focusing on depression, anxiety and schizophrenia. Before I discuss this, we need to see which parts of the brain to focus on.

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The main part of the brain responsible for these changes is the hippocampus, which is linked to feelings and emotion. Scientists who study mental illness believe in an imbalance in brain chemicals contributes to the development of many disorders.

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So how does depression affect the brain?

Originally scientists believed that the lack of neuro-transmitter called serotonin was to blame, this is also known as the “feel good” chemical.

However the only real evidence for this was when some depressed people were prescribed drugs which increased serotonin levels it helped alleviate their symptoms.

In recent years’ scientists began to notice that the brain cell growth and connections may actually play a larger role.

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When we look at the brain of a depressed person, studies show that generally the hippocampus is much smaller than average. Other areas of the brain are also physically affected but this area in particular affects memory and emotion. The longer a person has been depressed the smaller the hippocampus becomes. The cells and networks deteriorate. Stress can be the leading factor as to the decrease in neurons in this area of the brain.

Studies show that when this area of the brain is regenerated and new neurons are stimulated mood improves

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Many modern drugs, many of which include serotonin, have an indirect effect on the growth of brain cells. This is why serotonin base drugs seem to help some patients. But not for the reasons we once thought, instead they promote the release of other (next slide) chemicals which ultimately stimulate the growth of new neurons which is called neurogenesis. Knowing this scientist believe we should focus on developing drugs which focus on neurogenesis.

But while your neurons and chemicals may be the direct influencers, genetic factors have been discovered as well.

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Anxiety:

The amygdala, for example, plays a central role in anxiety disorders. This structure in thelimbicsystem warns us when a danger is present in our environment and triggers the fear reaction and then the fight or flight reaction to get us out of it.

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It is therefore no surprise that the central part of the amygdala seems to play an important role in anxiety disorders that involve specific fears, such as phobias. Researchers have also observed that a group of very anxious children had larger amygdalas, on average, than a group of children without anxiety.

The hippocampus is another essential limbic structure that specializes in encoding information. Because all old memories depend on the hippocampus, it would be surprising if this structure were not involved in anxiety disorders that are generated by memories of painful experiences, such as post-traumatic stress disorder(PTSD).

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7Schizophrenia:(next slide)

Scientists think that an imbalance in the complex, interrelated chemical reactions of the brain involving the neurotransmitters dopamine and glutamate, and possibly others, plays a role in schizophrenia. Neurotransmitters are substances that brain cells use to communicate with each other. Scientists are learning more about how brain chemistry is related to schizophrenia.

Glutamate is a powerful neurotransmitter that is released by nerve cells in the brain. It is responsible for sending signals between nerve cells, and under normal conditions it plays an important role in learning and memory.

In the brain, dopamine functions as a neurotransmitter—a chemical released by neurons (nerve cells) to send signals to other nerve cells. The brain includes several distinct dopamine pathways, one of which plays a major role in reward-motivated behaviour.(next slide)

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8Also, the brain structures of some people with schizophrenia are slightly different than those of healthy people. For example, fluid-filled cavities at the centre of the brain, called ventricles, are larger in some people with schizophrenia. The brains of people with the illness also tend to have less grey matter, and some areas of the brain may have less or more activity.

Studies of brain tissue after death also have revealed differences in the brains of people with schizophrenia. Scientists have found small changes in the location or structure of brain cells that are formed before birth. Some experts think problems during brain development before birth may lead to faulty connections. The problem may not show up in a person until puberty. The brain undergoes major changes during puberty, and these changes could trigger psychotic symptoms in people who are vulnerable due to genetics or brain differences. Scientists have learned a lot about schizophrenia, but more research is needed to help explain how it develops.(next slide)

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If a person does develop depression, the most common ways it affects the body is headaches, insomnia and muscle aches and joint pain. Similarly, if someone develops and anxiety disorder they may become nauseous, lightheaded or have a racing heartbeat. If someone has schizophrenia they may be suffering from insomnia or excessive sleeping, clumsiness or have a blank facial expression.